Unidirectional pumping seal



June 2, 1970 1.; H. WEVINAND 3,515,395

UNIDIRECTIONAL PUMPING S EAL Filed Sept. 6, 1966 2 Sheets-Sheet l INVIJN'IOR I 012216 .4 Klezkzazzd BY yral June 2, 1970 L. H. WEINAND3,515,395

' UNIDIRECTIONAL PUMPING SEAL Filed Sept. 6, 1966 2 Sheets-Sheet 2INVIL'NIUR Loaz's H [Va/Warm ATTORNEY United States Patent 3,515,395UNIDIRECTIONAL PUMPING SEAL Louis H. Weinand, Warren, Mich., assignor toGeneral Motors Corporation, Detroit, Mich., a corporation of DelawareFiled Sept. 6, 1966, Ser. No. 577,236 Int. Cl. F16j 15/32, 15/54 US. Cl.277-134 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates tohydrodynamic seals and more particularly to a hydrodynamic seal adaptedto seal a shaft irrespective of the direction of shaft rotation relativeto the sealing member.

The use of a helical groove or screw thread for generating hydrodynamicforces which serve to seal a rotating shaft is 'well known in the art.Such means of sealing, however, have been limited to applications inwhich the shaft rotates in only one direction because the hydrodynamicforces, which effectively maintain a fluid within its reservoir whilethe shaft is rotating in one direction, will increase leakage by pumpingthe fluid from its reservoir past the seal member if the direction ofshaft rotation is reversed.

The present invention provides a hydrodynamic seal which effectivelypumps the fluid in one direction irrespective of the direction of shaftrotation. The sealing arrangement contemplated by this inventionincludes a shaft rotatable in both clockwise and counter-clockwisedirections and a sealing member having a resilient annuluscircumferentially surrounding the shaft to contain a fiuid located toone side of the sealing member. The sealing member has a sealing surfacein contact with the shaft surface. A plurality of generally V-shapedgrooves are formed about the circumference of one of the engagedsurfaces and these grooves coact with the other surface to establishhydrodynamic forces for containing the fluid within its reservoir. Asthe shaft rotates, viscous drag imparts a circumferential motion tofluid near the shaft surface. Depending upon the direction of shaftrotation, the fluid entering the groove is directed against one of theopposed angled surfaces of the V-shaped grooves and is displacedtherefrom toward the fluid reservoir. If the direction of shaft rotationis reversed, the fluid within the grooves will be directed against theother of the opposed surfaces and will similarly be returned to thefluid reservo1r.

One feature of this invention is that it provides a hydrodynamic sealwhich effectively seals a fluid irrespective of the direction of shaftrotation.

Another feature of this invention is that it provides a hydrodynamicseal having a number of V-shaped grooves formed in one of the engagedsurfaces which coact with the other surface to generate hydrodynamicforces for dynamically sealing a fluid.

Yet another feature of the invention is that one of the angled sidewalls of the V-shaped groove is effective to' dynamically seal a fluidby means of hydrodynamic force 3,515,395 Patented June 2, 1970 ice whenthe shaft rotates in one direction and the opposed angled side wall iseffective for sealing when the shaft rotates in the opposite direction.

Still another feature of the invention is that the seal includes meansfor sealing a fluid while the members are stationary.

The features of the invention will be made apparent in the followingdetailed description taken in conjunction with the accompanying drawingswherein:

FIG. 1 is a view, partially broken away and in section, of a sealinstallation embodying seal means according to the present invention;

FIG. 2 is a view taken generally in a plane indicated by the line 22 ofFIG. 1;

FIG. 3 is an enlarged view taken generally in a plane indicated by theline 33 of FIG. 1;

FIG. 4 is a sectional view of a modified sealing member;

FIG. 5 is a view similar to FIG. 1 of another embodiment of the presentinvention;

FIG. 6 is a sectional view taken generally in a plane indicated by theline 6-6 of FIG. 5;

FIG. 7 is a sectional view of another embodiment of the presentinvention;

FIG. 8 is a sectional view of the seal shown in FIG. 7;

FIG. 9 is a view taken generally in a plane indicated by line 99 of FIG.8;

FIG. 10 is a view taken generally in a plane indicated by line 1010 inFIG. 9; and

FIG. 11 is a view showing the sealing engagement between the shaft andthe seal for the seal installation shown in FIG. 7.

Referring to FIG. 1, a seal installation 10 includes a shaft 12 havingan outer cylindrical surface 14 to be sealed and a seal 16 mountedwithin a housing 18. The seal 16 comprises an elastomeric sealing member20 having an annular sealing surface 22 in sealing engagement withsurface 14. The shaft 12 and the seal 16 are rotatable relative to eachother about their common axis 24 while the fluid being sealed is locatedto one side 25 of the seal 16 between the shaft 12 and the housing 18.

The elastomeric sealing member 20 includes a flex section 26 bonded atone end thereof to an annular metallic casing 28 located within ashouldered bore 30 in housing 18. A spring member 32 encircles thesealing member 20 and applies a predetermined radial load for urging thesurface 22 of sealing member 20 into sealing engagement with surface 14.Spring member 32 may be a garter spring as shown in FIG. 1 or any othersuitable type spring.

A number of equally spaced, generally V-shaped grooves 34 are cut orotherwise formed in the radially extending face 36 of sealing member 20.Grooves 34 extend through the sealing member 20 and form a V- groovedpattern in sealing surface 22. Each of the grooves so formed has opposedangled side walls 38 and 40 which are adapted to generate hydrodynamicforces for containing the fluid within its reservoir identified by thenumeral 25 while the shaft 12 is in motion. The included angle betweenside walls 38 and 40 as well as the number of grooves utilized will varyaccording to the sealing requirements of the specific seal installation.In the embodiment shown in FIG. 3 the included angle (A) is The groovedportion of the sealing surface 22 is backed by a circumferentiallyextending static sealing lip 42 'which interferingly engages the surface14 to seal the fluid while the shaft is at rest.

It will be noted that the radially extending face 36 and the grooves 34as shown in the preferred form of FIG. 1 extend generallyperpendicularly to the shaft surface 14. As seen in the modified form ofFIG. 4, however, face 36 and grooves 34 therein may be angled to thesurface 14. It should also be noted that the sealing surface 22 of boththe modified and preferred forms is angled slightly radially outwardbeginning at the face 36 when not engaged with the shaft as illustratedby angle (B) shown in FIG. 4. This ensures that the V-grooved portion ofthe sealing surface 22 will engage surface 14 when the seal 16 isinterferingly mounted on shaft 12.

An understanding of the operation of the unidirectional pumping seal maybest be gained by referring to FIGS. 1 and 3. The fluid reservoir is tothe right of seal 16 in FIG. 1 and clockwise rotation of shaft 12 willbe assumed when viewed from the right. As shaft -12 rotates, viscousshear forces set the fluid in motion circumferentially about the shaftsurface 14. For descriptive purposes a fluid particle a is shown in FIG.3 to illustrate the pumping action or fluid flow under the describedconditions. Fluid moving toward side Wall 38 impinges thereagainst andis directed along the angled surface to be displaced from left to rightas indicated by the arrows in FIG. 3. Thus, the fluid is displacedtoward the fluid reservoir 25 and away from the seal. If the directionof rotation of the shaft is reversed, a similar fluid displacement isachieved. In other words, with the shaft moving counterclockwise thefluid is directed against side wall 40 as indicated by the arrows andparticle b in FIG. 3 and is again displaced from left to right away fromthe seal to balance the energy potential tending to cause the fluid toflow past the seal. The above is a simplification of the actual fluidflow process involved, but serves to demonstrate that the fluid flowinduced by the pumping action of the V-groove surfaces is unidirectionalirrespective of the direction of shaft rotation. It is to be understoodthat only one side wall of the V-groove is effective as a pumping memberwhen the shaft rotates in one direction. Thus, if surfaces 38 are theeffective pumping members, surfaces 40 are ineffective and have notendency to pump fluid past the seal. The same is true of surfaces 38 ifthe rotation of the shaft is reversed and surfaces 40 become the pumpingmembers.

Another embodiment of the invention is illustrated in FIG. and it willbe noted that those parts corresponding to the parts in the embodimentof FIG. 1 are identified by the same numerals. According to thisembodiment, a plurality of circumferentially aligned V-shaped grooves 44are formed in surface 14 of shaft 12. Each groove 44 is formed as atriangularly-shaped recess in surface 14 and each has angled side Walls46 and 48, with an included angle (A). Grooves 44 are preferably equallyspaced about surface 14 and arranged with their walls 50 in a planenormal to axis 24. The number of grooves and the included angle beweensurfaces 46 and 48 may be varied depending upon the sealing conditions.The recesses in the shaft surface are preferably shallow and willnormally be less than .002 inch deep.

The seal installation further includes a conventional lip seal 52 havingan elastomeric sealing member 54 including inclined inner surface 55encircled by spring member '56 to urge a seal lip 58 into sealingengagement with surface 14. The seal lip 58 engages each groove 44 at apoint intermediate the length of side walls 46 and 48. With shaft 12 atrest, resilient member 54 of seal '52 is interferingly engaged withsurface 14. Due to the flexibility of member 54, the seal lip 58 is ableto assume a deformed shape and conform to the irregular shaft surfacecomprised of lands 60 and grooves 44. This creates a static seal forpreventing fluid from leaking beneath the seal while the shaft is atrest. With the shaft rotating, seal lip 58 rides on lands 60 free of thegrooves.

As shaft 12 rotates, seal lip 58 cooperates with grooves 44 todynamically seal a fluid located to the right of seal 52 in FIG. 5 inthe same manner as previously de scribed in the first embodiment. As theshaft rotates clockwise as viewed from the right in FIG. 5, surface 46acts as a miniature hydrodynamic pump to displace the fluid from left toright toward the fluid reservoir. If shaft ro- 4 tation is reversed,surface 48 pumps the fluid back to the reservoir. Whe nthe shaft stops,seal lip 58 again blocks the grooves to seal the shaft surface.

In a further modification shown in FIGS. 7 through 11, a plurality ofV-shaped grooves 44', similar to the grooves 44 of FIG. 5, are formed inthe frustoconical surface 55' of the lip seal 52'. Referring to FIG. 7,the surface 55' is on the air side of the lip seal 52' and is spacedfrom the fluid reservoir 25' by a seal lip 58'. As seen in FIG. 10, thegrooves 44 are generally triangular in shape and are defined by a basewall 50 and inclined walls 46' and 48' which converge away from the seallip 58' and the fluid reservoir 25'.

The grooves 44' are evenly spaced about the circumference of the surface55 and are separated by lands As shown in FIGS. 7 and 11, the grooves44' have their bases at the seal edge in engagement with the smoothcylindrical surface 14' of the shaft 12'. The grooves 44' have a depthof approximately 0.002 to 0.004 inch in the preferred arrangement toform recesses in the seal lip 58 which in this embodiment has a widthsufficient to accommodate the grooves 44' and to form a static sealingsurface 62' intermediate the grooved surface 55' and fluid reservoir25'.

This embodiment functions in substantially the same manner as describedwith reference to the FIG. 3 embodiment. As seen in FIG. 11, the fluidreservoir 25' is to the right of the static sealing surface 62'. As theshaft rotates in one direction, a fluid particle a impinges against theinclined wall 48 and is pumped from left to right past the sealingsurface 62' to the fluid reservoir 25'. For the opposite direction ofthe shaft rotation, a fluid particle b impinges against the inclinedwall 46 and is pumped from left to right past the sealing surface 62 tothe fluid reservoir 25.

This sealing arrangement has provide to be very effective due largely tothe fact that it has been found that such grooves when recessed but afew thousandths of an inch into the sealing surface, have acomparatively high pumping rate and sealing potential. The arrangementalso is considered advantageous because the grooves pump back the oilafter it has leaked past the static seal lip. The seal lip is thereforeassured of continuous lubrication with accompanying greater useful lifedue to a slow wear rate.

Various changes and modifications may be made to the above-describedembodiment without departing from the spirit of the invention. Suchchanges and modifications are contemplated by the inventor who does notwish to be limited except by the scope of the appended claims.

I claim:

1. A hydrodynamic seal, comprising: an annular casing; an annularsealing member formed of an elastomeric material attached to saidcasing, said sealing member having converging frustoconical surfacesintersecting at an annular seal edge; a plurality of recesses formed inone of the surfaces, each of said recesses being defined by a pair ofwalled surfaces converging away from said seal edge, each of said walledsurfaces having a base adjacent said seal edge, said recesses beingmutually separated by lands and having a depth in the order of 0.002. to0.004 inch.

2. A hydrodynamic seal for statically and dynamically sealing abidirectionally rotatable shaft, comprising: an annular casing; anelastomeric sealing member attached to said casing, said sealing memberhaving converging frustoconical surfaces intersecting at a radiallyinwardly facing seal edge; a. plurality of evenly spaced grooves formedin one of said surfaces, said grooves having a depth of approximately0.002 to 0.004 inch and being defined by pairs of inclined wallsconverging away from said seal edge and a base wall interconnecting saidinclined walls adjacent said seal edge; lands mutually separating saidgrooves, said seal edge and said lands being engage able with the shaftto form a static sealing surface therebetween, said inclined walls beingalternately operative to oppose fluid leakage past said seal edge uponreversal of shaft rotation.

3. A hydrodynamic seal for sealing the space between rotatable membersirrespective of the direction of relative rotation and preventing theflow therepast of fluid from a reservoir, comprising: an elastomericsealing annulus mounted on one of the members and having convergingfrustoconical surfaces defining a contact surface which is engageablewith an annular surface on the other of said members; pairs ofoppositely angled walled surfaces formed on the frustoconical surfacespaced from said reservoir by said contact surface, said walled surfacesconverging away from said reservoir and having base portions engageablewith said annular surface adjacent said contact surface, one of saidwalled surfaces being effective to generate hydrodynamic forces forpumping fluid leaking past said contact surface to the reservoir whenthe members are relatively rotating in one direction, the other of saidwalled surfaces being effective to generate hydrodynamic forces forpumping fluid leaking past said contact surface to the reservoir whenthe members are relatively rotating in the other direction.

4. A hydrodynamic seal for preventing the leakage of fluid from a fluidreservoir under static and dynamic operating conditions betweenbidirectionally relatively rotatable members, said seal comprising: anelastomeric sealing member mounted on one of the members havingconverging frustoconical surfaces defining a contact surface which isengageable with an annular surface on the other of said members; aplurality of circumferentially spaced recessed regions on thefrustoconical surface spaced from the fluid reservoir by said contactsurface that are defined by pairs of Walled surfaces converging awayfrom the fluid reservoir and having base portions engageable with saidannular surface adjacent said contact surface, one of said walledsurfaces being effective to generate hydrodynamic forces for pumpingfluid leaking into said regions past said contact surface to thereservoir when the members are relatively rotating in one direction, theother of said walled surfaces being effective to generate hydrodynamicforces for pumping fluid leaking into said regions past said contactsurface to the reservoir when the members are relatively rotating in theother direction.

5. A hydrodynamic seal for preventing the leakage of fluid from a fluidreservoir under static and dynamic operating conditions betweenbidirectionally rotating members, said seal comprising: an elastomericmember mounted on one of the members and having converging frustoconicalsurfaces intersecting at a continuous circumferential static seal edgewhich is engageable with the other of said members; a circumferentiallyspaced series of grooves formed in the frustoconical surface spaced fromsaid fluid reservoir by said seal edge which are mutually separated bylands, each of said grooves being defined by pairs of inclined wallsconverging away from said seal edge and a base wall interconnecting saidinclined Walls adjacent said seal edge, said seal edge and said landsbeing engageable with said other member to form a static sealing surfacetherebetween and said inclined walls being alternately operative tooppose fluid leakage past said seal edge upon reversal of shaftrotation.

6. A unidirectional pumping seal for sealing a bidirectionally rotatableshaft, comprising: an annular casing; an elastomeric sealing memberattached to the casing, said sealing member having convergingfrustoconical surfaces intersecting at a continuous circumferentialstatic seal edge which is engageable with the shaft; a circumferentiallyspaced series of grooves formed in one of said frustoconical surfaces,said grooves having an operative depth of less than .004 inch adjacentsaid seal edge and being defined by pairs of inclined walls convergingaway from said seal edge and a base wall interconnecting said inclinedwalls adjacent said seal edge; and lands mutually separating saidgrooves, said seal edge and said lands being engageable with the shaftto form a static sealing surface therebetween, said inclined walls beingalternately operative to oppose fluid leakage past said seal edge uponreversal of shaft rotation.

7. The invention as recited in claim 6 wherein said grooves aregenerally V-shaped and said inclined walls are substantially straightand intersect on said one of said frustoconical surfaces at an apexremote from said seal edge.

8. The invention as recited in claim 6 wherein spring means retained onsaid sealing member serves to radially inwardly bias said seal edge.

References Cited UNITED STATES PATENTS 1,811,588 6/1931 Moreau 277-1343,059,938 10/ 1962 Hennessy 277134 X 2,188,857 1/1940 Chievitz 277-134 X2,446,380 8/ 1948 Meyers et al 277-134 X 2,958,551 11/1960 Rogers277-134 X 3,259,393 7/1966 Dega 277-134 FOREIGN PATENTS 499,480 1/ 1939Great Britain.

673,726 6/1952 Great Britain.

888,198 1/ 1962 Great Britain. 1,342,278 9/1963 France.

SAMUEL ROTHBERG, Primary Examiner UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. 3 515 395 Dated June 2 1970Inventor) Louis H. Weinand It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 3 line 49 "their walls 50 in a plane" should read their basewalls 50 in a plane Column 4 line 2 "W'he nthe" should read When theSigned and sealed this 3rd day of November 1970 (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting OfficerCommissioner of Patents FORM PO-105O (IO-6S) USCOMM-DC 60376-P09 u soeovnuncur rnnmna orrlcz: nu o-au-su

